std::is_constructible, std::is_trivially_constructible, std::is_nothrow_constructible — cppreference.com

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Déclaré dans l'en-tête `<type_traits>`
`template< class T, class... Args > struct is_constructible;`	(1)	(depuis C++11)
`template< class T, class... Args > struct is_trivially_constructible;`	(2)	(depuis C++11)
`template< class T, class... Args > struct is_nothrow_constructible;`	(3)	(depuis C++11)

Si le T obj(arg1, arg2, ... argN); expression est bien formée, étant donné les références rvalue à Args... comme arguments, fournit du membre de constante value true égale. Pour tout autre type, value est false .

Original:

If the expression T obj(arg1, arg2, ... argN); is well-formed, given rvalue references to Args... as arguments, provides the member constant value equal true. For any other type, value is false.

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même que 1), mais l'expression constructeur n'appelle pas une opération qui n'est pas anodin .

Original:

same as 1), but the constructor expression does not call any operation that is not trivial.

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même que 1), mais l'expression constructeur est noexcept .

Original:

same as 1), but the constructor expression is noexcept.

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Inherited from std::integral_constant

Member constants


value [ statique Original: static The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. ]	`true` si `T` is constructible from `Args...` , `false` autrement Original: `true` if `T` is constructible from `Args...` , `false` otherwise The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (constante membre statique publique)

Member functions


	convertit l'objet en `bool`, retourne `value` Original: converts the object to `bool`, returns `value` The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (fonction membre publique)

Member types


Type d' Original: Type The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.	Definition

`value_type`	`bool`

`type`	`std::integral_constant<bool, value>`

Exemple

#include <iostream>
#include <type_traits>

class Foo {
    int v1;
    double v2;
 public:
    Foo(int n) : v1(n), v2() {}
    Foo(int n, double f) noexcept : v1(n), v2(f) {}
};

int main() {
    std::cout << "Foo is ...\n" << std::boolalpha
              << "\tTrivially-constructible from const Foo&? "
              << std::is_trivially_constructible<Foo, const Foo&>::value << '\n'
              << "\tTrivially-constructible from int? "
              << std::is_trivially_constructible<Foo, int>::value << '\n'
              << "\tConstructible from int? "
              << std::is_constructible<Foo, int>::value << '\n'
              << "\tNothrow-constructible from int? "
              << std::is_nothrow_constructible<Foo, int>::value << '\n'
              << "\tNothrow-constructible from int and double? "
              << std::is_nothrow_constructible<Foo, int, double>::value << '\n';
}

Résultat :

Foo is ...
        Trivially-constructible from const Foo&? true
        Trivially-constructible from int? false
        Constructible from int? true
        Nothrow-constructible from int? false
        Nothrow-constructible from int and double? true

Voir aussi


is_default_constructible is_trivially_default_constructible is_nothrow_default_constructible (C++11) (C++11) (C++11)	vérifie si un type a un constructeur par défaut Original: checks if a type has a default constructor The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (classe générique) [edit]

is_copy_constructible is_trivially_copy_constructible is_nothrow_copy_constructible (C++11) (C++11) (C++11)	vérifie si un type a un constructeur de copie Original: checks if a type has a copy constructor The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (classe générique) [edit]

is_move_constructible is_trivially_move_constructible is_nothrow_move_constructible (C++11) (C++11) (C++11)	vérifie si un type a un constructeur déménagement Original: checks if a type has a move constructor The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (classe générique) [edit]

uses_allocator (C++11)	vérifie si le type spécifié prend en charge les utilisations-allocateur de construction Original: checks if the specified type supports uses-allocator construction The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (classe générique) [edit]